1. Field of the Invention
The invention relates in general to a power system, and more particularly to a power server system.
2. Description of the Related Art
Referring to FIG. 1, a signal timing diagram of conventional BBU and power supply is shown. The power supply converts an AC power VAC into a DC power VDC1. When the AC power VAC is disconnected, the power supply generates an AC OK signal ACOK, and the power supply continues outputting the DC power VDC1 in a holding period Thold.
When the holding period Thold terminates, the power supply stops outputting the DC power VDC1, and the conventional battery backup unit (BBU) must instantaneously provide a redundant power VDC2 whose voltage level is the same with that of the DC power VDC1. However, the battery output current Iout' of the conventional BBU generates an increasing current at the instant when the power supply stops outputting the DC power VDC1. In addition, the battery output voltage Vout' of the conventional BBU drops dramatically at the instant when the power supply stops outputting the DC power VDC1.